As porous carbon materials, activated carbons having both macropores which are relatively large pores and micropores, such as particulate activated carbons and activated-carbon fibers; and fine carbons represented by carbon nanotubes and meso-porous carbons produced from a meso-porous silica or zeolite template, are known.
Of these, the activated carbons are in use as adsorbent materials and catalyst supports mainly in the field of industrial materials so as to take advantage of the large specific surface area thereof. In particular, since pores are formed by activating a bulk material which has been carbonized beforehand, the activated carbons further have an advantage in that porous materials can be supplied at relatively low cost. However, in general activation processes, pores are formed unidirectionally from the surface of the carbon material toward the inner part thereof and, hence, it is difficult to produce a material having communicating pores which are pores that communicate with one another. There has hence been a problem concerning application to composite materials, for example, because it is difficult to highly fill another material into the pores.
Patent Document 1 describes a technique for obtaining porous carbon fibers by mixing a carbonizable material with an eliminable material. However, the carbonizable material and the eliminable material are a combination which forms a non-compatible system, and the mere addition of a compatibilizing agent was unable to form continuous pores.
Patent Document 2 describes a technique in which the porous carbon fibers described in Patent Document 1 are further activated to form pores therein, thereby producing activated-carbon fibers. However, since the activation step is intended to form pores from the surface of the carbon material mainly by oxidation as stated above, this technique also failed to form continuous pores.
Patent Documents 3 and 4 show examples in which a carbon material which itself has a continuous porous structure introduced thereinto is produced by mixing a thermosetting resin with a thermoplastic resin, curing the thermosetting resin, subsequently removing the thermoplastic resin, and then performing carbonization.